Are "Numar Proiect", "Numar Ansamblu" and "Numar Component" already variables on this data card? If so then this will work..but not fantastically.
This input formula would only update when one of those three variables change manually. You would have to go to one of the three controls on the card containing a serial number and change it, then change it back...like add the letter J to the end then remove it. That change will trigger the update of the formula.
"Numar component" is not on this data card, is on another data card for part files.